1. Technical Field of the Invention
The present invention relates to a starting device for engines having an electromagnetic switch that opens and closes a main point of contact of a motor circuit and a solenoid device that pushes a pinion gear to an engine side.
2. Description of the Related Art
As conventional technology, a starting device for engines disclosed in Japanese Utility Model Application Laid-Open Publication No. 56-42437, for example, is well known. The starting device for engines comprises an electromagnetic switch that opens and closes a main point of contact of a motor circuit, an electromagnetic means (an electromagnet device) that pushes out a pinion gear to the engine side via a lever, and a detector that detects an engagement state of the pinion gear and a ring gear.
When the pinion gear is engaged with the ring gear after pushed out by the electromagnetic means to the engine side, and the engagement state of the pinion gear and the ring gear is detected by the detector, the electromagnetic switch is turned on and the main point of contact is closed. Consequently, the torque of the motor is transmitted to the ring gear via the pinion gear, and starts the engine.
By the way, an installing space of a starter for an automobile is usually the place right next to the engine, and, in many cases, functional components such as an intake manifold with higher priorities for the engine performance are arranged around the starter.
For this reason, since the starter that has only a starting function receives restrictions of an outer diameter size greatly in many cases, it becomes important to increase installing ability by miniaturizing the starter in order to secure the market competition power of the product itself.
By the way, regarding an electromagnetic switch equipped in a starter for automobiles, an electromagnetic switch for starters disclosed in Japanese Patent Application Laid-Open Publication No. 2007-242585 is well known as a conventional technology. The electromagnetic switch has a fixed iron core that is magnetized by the energization to an electromagnetic coil and a movable iron core attracted by the magnetized fixed iron core.
The electromagnetic switch interlocks with a motion of the movable iron core, and opens and closes an electric point of contact (main point of contact of a motor circuit). The fixed iron core is constituted by dividing it to a base part that is arranged facing the movable iron core and a disk part that fits into a perimeter of the base part and holds the base part, and the disk part is constituted with a plurality of laminated steel sheets.
When the above-mentioned electromagnetic switch is operated, that is, energizing the electromagnetic coil magnetizes the fixed iron core, the movable iron core made of soft steel collides the base part made of soft steel so that a loud collision noise occurs.
At this time, since the disk part of the fixed iron core is constituted with a plurality of laminated steel sheets, propagation of vibration generated by the collision with the movable iron core and the base part is suppressed. By this, although the noise emitted to the exterior is reduced to some extent, since the collision noise itself is not reduced, the effect of reducing the operation noise of the electromagnetic switch is not so large.
On the other hand, although adoption of an idol stop system etc. is predicted to be increased from now on for the improvement in fuel consumption resulting from a global warming issue, since number of times of starting the engine will increase rapidly if the idol stop system is adopted, the improvement in durability of the starter is needed.
Moreover, if the number of the vehicles equipped with the idol stop system increases, the number of the case where many vehicles start the engines all at once on the public streets under traffic congestion will increase, therefore the noise generated at the time of starting the engines (generated noise) increases, and noise problem generated around streets is assumed.
Furthermore, in order to cope with the problem of global warming in recent years, also in the car using an internal-combustion engine, the motion that introduces the so-called idol stop system that improves fuel consumption is accelerating by stopping the engine for the purpose of reducing carbon dioxide (CO2) at the time of a stop.
Specifically, regarding durability, improvement in life of brushes used for a starter motor, and durability of a pinion gear and a ring gear will become main items. Although long-life brushes for the motors have been developed that the material is paid attention to, since the pinion gear and the ring gear are on the premise to be engaged on condition of no lubrication, the improvement of the material and the improvement of the method of engagement itself are needed.
In improvement of the method of the engagement, it is effective to keep proper extrusion of the pinion gear and the energization timing to the motor, and regarding these points, the well-known technology disclosed in the above-mentioned Publication No. 56-42437 is effective.
However, the electromagnetic switch that opens and closes the main point of contact of the motor circuit and the electromagnetic means that pushes out the pinion gear to the engine side are provided separately in the technology disclosed in the above-mentioned Publication No. 56-42437.
At the same time, the both are arranged parallel in the circumferential direction of the motor. With this composition, since a size increases in two directions in a radical direction to a main axis of the motor, a big disadvantage on the sizes arise in respect of installing the starter to the engine.
That is, in the ordinary starter that has one electromagnetic switch for one motor, in order to avoid interference with other parts arranged around the engine, the electromagnetic switch is shifted at a proper angle in the circumferential direction to the main axis of the motor for the solution.
However, since the electromagnetic switch and the electromagnetic means are arranged parallel in the circumferential direction of the motor in the starter disclosed in the above-mentioned Publication No. 56-42437, avoiding interference with other parts in two directions in the radical direction to the main axis of the motor seems to have many difficulties.
On the other hand, regarding the noise problem, in order to spread an idol stop system, reduction of the generated noise in connection with starting the engines becomes a subject. Among these, noises generated at the time of starting in the starter are a gear engagement noise that is generated when the pinion gear engages to the ring gear provided on the engine side, and an operation noise of the electromagnetic switch.
Since the operation noise of the electromagnetic switch is the noise generated at the moment of turning on the electromagnetic switch, i.e., the collision noise generated when the movable iron core collides with the fixed iron core is the loudest. Therefore, to reduce the collision noise becomes important to reduce the generated noise at the time of starting the engine.
On the other hand, Japanese Utility Model Application Laid-Open Publication No. 49-27140 and Japanese Patent Application Laid-Open Publication No. 59-65665 are well known as conventional technology regarding the gear.
In the Publication No. 49-27140, there is proposed a laminated type gear that forms a lamination structure object by laminating a large number of metal plates having tooth part in their perimeter, producing an elastic action to the structure object by press modifying a bowl-like metal object from the both sides of this lamination structure object, and integrating this lamination structure object by pinching it from both sides with the elastic action.
In the Publication No. 59-65665, there is proposed a gear that laminates several thin plates having tooth portions formed in their perimeter, and welds each other by electron beam welding at a tooth bottom and at a tooth top of each thin plate.
By the way, among the gear noise generated between the pinion gear and the ring gear, there are gear end surface collision noises generated when the end surface of the pinion gear collides with the end surface of the ring gear, and the gear engagement noises generated when the pinion gear engages to the ring gear and rotates.
However, when the gears disclosed in the Publication No. 49-27140 and the Publication No. 59-65665 are used as the pinion gear, since the gears shown in both publications are the laminated objects, it is possible to reduce the gear engagement noise, but the effect of reducing the gear end surface collision noise is not expectable.
That is, the gear shown in the Publication No. 49-27140, like mentioned above, is press modifying the bowl-like metal object from the both sides of the lamination structure object to produce the elastic action, pinching the lamination structure object from both sides with the elastic action tightly, and the whole gear is fixed in the axial direction by rivets, etc.
For this reason, the adhesion nature of each laminated metal plates is very high, and even if the gear is the lamination structure object, the whole gear is considered to have rigidity equivalent to one rigid body (for example, a pinion gear manufactured by cutting from a steel material, forging in the colds, etc.).
In this structure, since each metal plate (especially tooth part) that constitute the pinion gear cannot be bent mutually at the time the pinion gear collides with the ring gear when the gear shown in the Publication No. 49-27140 is used as the pinion gear with, it is difficult to reduce gear end surface collision noise.
Moreover, since the tooth bottom and the tooth top of the tooth portion formed on each laminated thin plate are welded each other by electron beam in the gear shown in the Publication No. 59-65665, the tooth portion of each thin plate cannot bend mutually.
For this reason, even when the gear shown in the Publication No. 59-65665 is used as the pinion gear like the case of the Publication No. 49-27140, it is difficult to reduce the gear end surface collision noise generated when the pinion gear collides with the ring gear.